With conventional techniques, in a case of employing multiple rechargeable batteries, such an arrangement requires a cell balance mechanism to equalize the respective charge voltages of the multiple rechargeable batteries. Thus, in some cases, a resistor is connected in parallel to each of the multiple rechargeable batteries. Such an arrangement allows a rechargeable battery having a higher charge voltage than those of the other rechargeable batteries to be discharged via the resistor thus connected in parallel. Thus, such an arrangement equalizes the respective charge voltages of the multiple rechargeable batteries.
However, such an arrangement in which a resistor is connected in parallel to each rechargeable battery has a problem of large power loss due to the discharging via the resistors. In order to solve such a problem, circuits have been proposed as disclosed in Patent documents 1 and 2.